1. Field of the Invention
The present invention relates to a burner for the formation and combustion of an ignitable mixture of liquid fuel and combustion air, which includes a closed combustion chamber for the infeed of the fuel with porous walls permeable to the fuel. The combustion chamber is arranged within a flow chamber which is streamed through by preheated combustion air flowing towards the combustion zone.
The invention is also directed to a burner for the formation and combustion of the ignitable mixture of liquid fuel and combustion air which includes a fuel chamber fillable with fuel for the infeed of the fuel, which is equipped with porous walls permeable to the fuel and is hydraulically displaceably arranged within a combustion chamber, which is streamed through by preheated combustion air towards the combustion zone, in opposition to a counter force, wherein a hydraulic cylinder which guides the fuel chamber includes a connection for the inlet of fuel as the hydraulic operating medium, and a fuel conduit leads from the fuel-filled inner space of the hydraulic cylinder towards the inner space of the fuel chamber, and wherein there is also provided a discharge for the fuel leading from the fuel chamber through the inner space of the hydraulic cylinder.
2. Discussion of the Prior Art
Burners of this type are determined for industrial furnaces, as well as for heat generators of smaller sized unit. In these burners the liquid fuel passes through the porous walls of the fuel chamber and vaporizes in the preheated combustion air streaming through the combustion chamber. As a result of the vaporization of the liquid fuel on the surface of the porous walls there is prevented an undesirable overheating of the liquid fuel which would lead to cracking. In the combustion chamber, the fuel and combustion air are mixed together and introduced as an ignitable mixture into the combustion zone. In this connection, reference may be had to German Laid-open Patent Appln. No. 29 12 519.
It is intended to so conduct the switching on and switching off phases of the burner that the lowest possible fuel losses will occur. In general, during cold starting, fuel losses are produced in that a portion of the fuel which is conducted to the burner, due to the still too low burner temperature, is conveyed unburned into the exhaust gas and, consequently, pollutes the environment. Moreover, at the switching off of the burner, measures must be taken for the prevention of fuel losses. Thus, during the vaporization of fuel in the preheated combustion air at switching off there must be avoided a post-vaporization as well as any other further egress of fuel into the combustion chamber. The latter is also necessary due to technical safety reasons in that particularly during operational failures, no after-burning will take place.
For the control of the switching on and switching of phases of the burner provision is made that the fuel chamber of the burner is displaceably arranged in the space which is streamed through by the preheated combustion air so as to be able to regulate the delivery of fuel into the combustion air and in order to avoid fuel losses or an undesirable after-burning subsequent to the switching off of the burner. The fuel chamber is arranged to be hydraulically displaceable wherein the fuel which is to be conducted into the combustion chamber serves concurrently as the hydraulic fluid. This requires the provision of suitable sealing means intermediate the inner space of the hydraulic unit which is under super-atmospheric pressure and the space which is streamed through by the combustion air, as well as the environment, in order to maintain any leakages as low as possible during the adjustment of the fuel chamber.